[PATCH v5 2/4] backlight: aat2870: Derive brightness steps from max current

[Svyatoslav Ryhel]

The AAT2870 allows only 32 steps of brightness, with this amount defined
by the maximum supported current. Remove the need for max_brightness by
calculating the allowed number of steps from the maximum current.

Reviewed-by: Daniel Thompson (RISCstar) <danielt@xxxxxxxxxx>
Signed-off-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>
---
 drivers/video/backlight/aat2870_bl.c | 35 +++++++++-------------------
 1 file changed, 11 insertions(+), 24 deletions(-)

diff --git a/drivers/video/backlight/aat2870_bl.c b/drivers/video/backlight/aat2870_bl.c
index 8b790df1e842b..e85f2b4d81068 100644
--- a/drivers/video/backlight/aat2870_bl.c
+++ b/drivers/video/backlight/aat2870_bl.c
@@ -20,22 +20,9 @@ struct aat2870_bl_driver_data {
 	struct backlight_device *bd;
 
 	int channels;
-	int max_current;
 	int brightness; /* current brightness */
 };
 
-static inline int aat2870_brightness(struct aat2870_bl_driver_data *aat2870_bl,
-				     int brightness)
-{
-	struct backlight_device *bd = aat2870_bl->bd;
-	int val;
-
-	val = brightness * (aat2870_bl->max_current - 1);
-	val /= bd->props.max_brightness;
-
-	return val;
-}
-
 static inline int aat2870_bl_enable(struct aat2870_bl_driver_data *aat2870_bl)
 {
 	struct aat2870_data *aat2870
@@ -69,10 +56,11 @@ static int aat2870_bl_update_status(struct backlight_device *bd)
 	dev_dbg(&bd->dev, "brightness=%d, power=%d, state=%d\n",
 		 bd->props.brightness, bd->props.power, bd->props.state);
 
-	ret = aat2870->write(aat2870, AAT2870_BLM,
-			     (u8)aat2870_brightness(aat2870_bl, brightness));
-	if (ret < 0)
-		return ret;
+	if (brightness) {
+		ret = aat2870->write(aat2870, AAT2870_BLM, (u8)brightness - 1);
+		if (ret < 0)
+			return ret;
+	}
 
 	if (brightness == 0) {
 		ret = aat2870_bl_disable(aat2870_bl);
@@ -145,15 +133,14 @@ static int aat2870_bl_probe(struct platform_device *pdev)
 	else
 		aat2870_bl->channels = AAT2870_BL_CH_ALL;
 
+	/*
+	 * The maximum number of brightness steps is determined by the max current.
+	 * The aat2870_current enum maps directly to the allowed brightness steps.
+	 */
 	if (pdata->max_current > 0)
-		aat2870_bl->max_current = pdata->max_current;
-	else
-		aat2870_bl->max_current = AAT2870_CURRENT_27_9;
-
-	if (pdata->max_brightness > 0)
-		bd->props.max_brightness = pdata->max_brightness;
+		bd->props.max_brightness = pdata->max_current;
 	else
-		bd->props.max_brightness = 255;
+		bd->props.max_brightness = AAT2870_CURRENT_27_9;
 
 	aat2870_bl->brightness = 0;
 	bd->props.power = BACKLIGHT_POWER_ON;
-- 
2.53.0